As disclosed in U.S. Pat. No. 7,193,015, the incorporation of externally fluorinated POSS into fluorinated polymers further reduces their surface energy and contact angle rendering them super hydrophobic. It is the objective of this application to convey the ability of fluorinated POSS to impart “fluoropolymer type” characteristics to nonfluorinated polymers, metal surfaces, particulates, composites and biological systems.
It has long been recognized that the properties of polymers can be tailored to a high degree through variables such as polymer sequence, structure, additive and filler incorporation, composition, morphology, thermodynamic and kinetic processing control. It is similarly known that various sizes and shapes of fillers, and particulates (e.g. Teflon®, calcium carbonate, silica, carbon black, etc.) can be incorporated into polymers, monomer mixtures, and composites to enhance physical properties.
In their solid state all polymers (including amorphous, semi-crystalline, crystalline, and rubber, etc.) possess considerable amounts of internal and external free volume and this free volume has a tremendous impact on physical properties, since it is within this volume that the dynamic properties (e.g. reptation, translation, rotation, crystallization, interaction with surfaces and fillers) of polymer chains primarily operate and in turn influence fundamental physical properties.
The accessibility of free volume in a polymer system depends greatly on morphology and on the size of the agent desired to occupy the free volume. Thermodynamic and kinetic properties, polymer morphology and free volume dimension are major factors, which limit the ability of conventional fillers from accessing the free volume in a polymer system. Significant processing/compounding effort is normally required to force compatibilization between fillers and polymers since conventional fillers are physically larger than most polymer dimensions, chemically dissimilar, and viscometricaly different than most polymers.
Prior art in nonfluoropolymers has utilize fluorinated additives and fluorinated filler particulates to impart characteristics of the fluorinated entity to the nonfluorinated polymer. Unfortunately, the prior art suffers from process complexity, inappropriate length scale of the reinforcement to access polymer free volume, or the reinforcement lacks sufficient geometrical definition to provide structural regularity and reinforcement at the molecular (10−10 m) and nanoscopic (10−9 m) length scales. Consequently many desirable properties of the nonfluorinated polymer are lost upon incorporation of conventional fluorinated components.
Furthermore, it has been calculated that as filler sizes decrease below 50 nm, they become more resistant to sedimentation and more effective at providing reinforcement to polymer systems. The full application of this knowledge, however, has been thwarted by the lack of a practical source of fluorinate particulates or fluorinated additives less than 50 nm and preferably with a rigid 1 nm to 5 nm size range. Particularly desirable are monodisperse, nanoscopic chemicals with precise chemical compositions, rigid and well defined geometrical shapes, and which are dimensionally large enough to provide reinforcement of polymer chains. Such nanoscopic chemicals are desirable as they form stable dispersions within polymer systems, well below the length scale necessary to scatter light and hence are visually nondetectable when incorporated. Further fluorinated nanoscopic chemicals would be chemically compatible with nonfluoropolymers and dissolve into and among the polymer chains, thus eliminating the need for the complex processing requirements of the prior art.
The fundamental premise behind this invention is underpinned mathematically through computation of the surface area and volume contribution provided at various loadings of 1 nm diameter fluorine containing nanostructured chemical entities into or onto a nonfluorinated polymeric material. Computation reveals that a fluorinated nanostructured chemical contributes more surface area and more volume as a wt % of its incorporation into a material than is possible for larger particles (see FIG. 1, FIG. 2, and FIG. 3). The net effect is that even small loadings of nanostructured chemicals can dominate the surface characteristics of a material. This is an important economic consideration since fluorinated materials are traditionally expensive and desired to be used in minimal quantities.
Further, the incorporation of fluorinated nanostructured chemicals onto the surface of a secondary material (such as TiO2, CaCO3, glass or mineral fillers, and fibers) can be utilized to creating more surface area on such particle and improve their compatibility with fluorinated and nonfluorinated polymers.
Recent developments in nanoscience have enabled the cost effective manufacture of commercial quantities of materials that are best described as nanostructured chemicals due to their specific chemical formula, hybrid (inorganic-organic) chemical composition, geometrically precise and rigid shape, large physical size relative to traditional chemicals (0.3-0.5 nm), and small physical size relative to larger sized traditional fillers (>50 nm).
Nanostructured chemicals are best exemplified by those based on low-cost Polyhedral Oligomeric Silsesquioxanes (POSS) and Polyhedral Oligomeric Silicates. FIGS. 4, 5, 6 illustrate some representative examples of fluorinated nanostructured chemicals, which are also referred to as fluorinated POSS in this application. It is recognized that oligomeric, polymeric, and metal containing versions of fluorinated POSS may also be utilized. Nanostructured chemicals based on polyhedral oligomeric silsesquioxanes and polyhedral metallosesquioxanes are discussed in detail in U.S. Pat. Nos. 5,412,053; 5,484,867; 6,329,490; and 6,716,919, which are expressly incorporated herein by reference in their entirety.